1. Field of the Invention
The present invention relates to a camera module, more particularly, a camera module having an array lens, the camera module which has a lower optical system along an optical axis for smaller size, keeps light refracted from an adjacent lens from affecting an image, blocks leakage of light for imaging and increases definition of the image through signal processing.
2. Description of the Related Art
Recently, with development in the electronic telecommunication industry, a mobile wireless terminal (hereinafter “terminal”) is increasingly reduced in weight and size and varied in function. Especially, a camera module based on a digital camera technology is incorporated into the terminal to be employed as a camera phone terminal with camera function. Through the commercially viable camera phone terminal, moving and still images of an object are photographed and stored, and transmitted to another person.
The camera module disposed integrally in this terminal is typically required to be small in size and light in weight. This camera module includes a plurality of lenses, a lens barrel where the lenses are sequentially arranged along an optical axis, a diffraction optical device diffracting light transmitted through the lenses and an image sensor where light transmitted through the diffraction optical device is imaged.
However, a rising demand for higher definition necessitates use of an image sensor with a high pixel number and increases the number of the lenses. In consequence, this complicates assembling of the lenses in the lens barrel and packaging of the lenses assembled in the lens barrel together with the image sensor. Also, the increasing number of the lenses enlarges the volume of the camera module.
To reduce the volume of the camera module and enhance definition, WO No. 2005/072370 discloses a manufacturing method of a camera module, in which a plurality of micro lenses are disposed coplanarly by a semiconductor process technology.
As shown in FIG. 1, the camera module 20 includes a lens group 22, a color filter 25, an image sensor 24 and a processor 30. The lens group 22 has a plurality of lenses 22a,22b,22c and 22d arranged in a 2×2 array on a surface or both surfaces of the camera module 20. The color filter 25 is disposed on a bottom surface of the lens group 22 which is stacked above another lens group. Light transmitted through the lenses 22a,22b,22c and 22d and the color filter 25 is imaged on the image sensor 24.
Accordingly, the light passing through the lenses 22a,22b,22c and 22d of the lens group 22 and the color filter 25 is imaged on an imaging region of the image sensor 24. Here, definition of an image formed in the image sensor is increased by moving the lenses by a half pixel.
In the meantime, when the light incident on an incident surface of the upper lens group 22 is refracted while passing through the lenses 22a,22b,22c and 22d, most of the light enters the lenses of the lower lens group along the same axis. However, the light refracted at a view angle greater than necessary is incident on an adjacent one of the lenses, thereby interfering with the normal incident light or leaking to an outer periphery of the lens group.
This interference and leakage of the light deteriorates definition of the image formed in the image sensor.